Methods of forming field effect transistors, methods of forming field effect transistor gates, methods of forming integrated circuitry comprising a transistor gate array and circuitry peripheral to the gate array, and methods of forming integrated circuitry comprising a transistor gate array including first gates and second grounded isolation gates

ABSTRACT

The invention includes methods of forming field effect transistors, methods of forming field effect transistor gates, methods of forming integrated circuitry comprising a transistor gate array and circuitry peripheral to the gate array, and methods of forming integrated circuitry comprising a transistor gate array including first gates and second grounded isolation gates. In one implementation, a method of forming a field effect transistor includes forming masking material over semiconductive material of a substrate. A trench is formed through the masking material and into the semiconductive material. Gate dielectric material is formed within the trench in the semiconductive material. Gate material is deposited within the trench in the masking material and within the trench in the semiconductive material over the gate dielectric material. Source/drain regions are formed. Other aspects and implementations are contemplated.

TECHNICAL FIELD

This invention relates to fabrication of field effect transistors andcomponents thereof.

BACKGROUND OF THE INVENTION

Field effect transistors are common devices utilized in integratedcircuitry, for example in logic circuitry, memory circuitry and controlcircuitry for memory circuitry. Such devices typically comprise a pairof source/drain regions having a channel region received therebetween. Aconductive gate is provided operably proximate the channel region, andis spaced therefrom by a gate dielectric region. Application of asuitable voltage to the conductive gate causes current flow between thesource/drain regions through the channel region.

By way of example only, the conductive material of the gate might beformed above or over semiconductive material or within openings formedin the semiconductive material, and for example whether within bulkmonocrystalline substrate material or within semiconductor-on-insulatormaterial. When formed within trenches or other openings insemiconductive material, some of such are referred to as recessed accessdevices. Here, masking material is provided over the semiconductivematerial of the substrate and patterned to form gate line trencheswithin the substrate. With the trenches so formed, the masking materialis removed, and then a gate dielectric is formed within the trenchopenings, for example by thermal oxidation of exposed semiconductivematerial within the trench. Gate material is then deposited to overfillthe trenches. The gate material received outwardly of the trenches isthen patterned, typically using photolithography and etch, to formdesired gate outlines over the trenches within which the gate materialis also received.

Typically, the gate material patterning forms the gate lines over thetrenches to be very close to or of the same width as the underlyingtrenches. Photomask misalignment can undesirably place an edge of thedesired gate line pattern within the lateral confines of the previouslyetched trench. This is highly undesirable, as the gate pattern etch canetch gate material within the trench, ultimately leading to circuitryfailure or at least unacceptable device configuration and performance.

While the invention was motivated in addressing the above identifiedissues, it is in no way so limited. The invention is only limited by theaccompanying claims as literally worded, without interpretative or otherlimiting reference to the specification, and in accordance with thedoctrine of equivalents.

SUMMARY

The invention includes methods of forming field effect transistors,methods of forming field effect transistor gates, methods of formingintegrated circuitry comprising a transistor gate array and circuitryperipheral to the gate array, and methods of forming integratedcircuitry comprising a transistor gate array including first gates andsecond grounded isolation gates. In one implementation, a method offorming a field effect transistor includes forming masking material oversemiconductive material of a substrate. A trench is formed through themasking material and into the semiconductive material. Gate dielectricmaterial is formed within the trench in the semiconductive material.Gate material is deposited within the trench in the masking material andwithin the trench in the semiconductive material over the gatedielectric material. Source/drain regions are formed.

In one implementation, a method of forming a field effect transistorgate includes forming a silicon nitride-comprising masking material oversemiconductive material of a substrate. A trench is formed through thesilicon nitride-comprising masking material and into the semiconductivematerial. Silicon nitride of the masking material is removed afterforming the trench into the semiconductive material. Prior to removingsilicon nitride of the masking material, gate dielectric material isformed within the trench in the semiconductive material. Gate materialis deposited within the trench in the semiconductive material over thegate dielectric material.

In one implementation, a method of forming integrated circuitrycomprising a transistor gate array and circuitry peripheral to the gatearray includes forming masking material over semiconductive material ofa substrate. Array circuitry trenches are formed through the maskingmaterial and into the semiconductive material. Array gate material isdeposited within the array circuitry trenches in the masking materialand within the array circuitry trenches in the semiconductive material.After depositing the array gate material, peripheral circuitry trenchesare formed through the masking material. Peripheral circuitry gatematerial is deposited within the peripheral circuitry trenches withinthe masking material.

In one implementation, a method of forming integrated circuitrycomprising a transistor gate array and circuitry peripheral to the gatearray includes forming masking material over semiconductive material ofa substrate. Array circuitry trenches are formed through the maskingmaterial and into the semiconductive material. Array gate material isdeposited within the array circuitry trenches in the masking materialand within the array circuitry trenches in the semiconductive material.Peripheral circuitry trenches are formed through the array gate materialand through the masking material. Peripheral circuitry gate material isdeposited within the peripheral circuitry trenches within the array gatematerial and within the masking material.

In one implementation, a method of forming field effect transistor gatesincludes forming masking material over semiconductive material of asubstrate. The substrate comprises a trench isolation region. In acommon masking step, a first trench is formed through the maskingmaterial and into the semiconductive material and a second groundedisolation gate trench is formed through the masking material over thetrench isolation region. In a common deposition step, gate material isdeposited within the first trench and second trench.

In one implementation, a method of forming integrated circuitrycomprising a transistor gate array including first gates and secondgrounded isolation gates comprises forming masking material oversemiconductive material of a substrate. The substrate comprises trenchisolation regions. First trenches are formed through the maskingmaterial and into the semiconductive material for the first gates.Second grounded isolation gate trenches are formed through the maskingmaterial over the trench isolation regions. Gate material is depositedwithin the first and second trenches.

Other aspects and implementations are contemplated.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic sectional view of a semiconductor substratefragment in process in accordance with an aspect of the invention.

FIG. 2 is a view of the FIG. 1 substrate fragment at a processing stepsubsequent to that shown by FIG. 1.

FIG. 3 is a view of the FIG. 2 substrate fragment at a processing stepsubsequent to that shown by FIG. 2.

FIG. 4 is a view of the FIG. 3 substrate fragment at a processing stepsubsequent to that shown by FIG. 3.

FIG. 5 is a view of the FIG. 4 substrate fragment at a processing stepsubsequent to that shown by FIG. 4.

FIG. 6 is a view of the FIG. 5 substrate fragment at a processing stepsubsequent to that shown by FIG. 5.

FIG. 7 is a view of the FIG. 6 substrate fragment at a processing stepsubsequent to that shown by FIG. 6.

FIG. 8 is a view of the FIG. 7 substrate fragment at a processing stepsubsequent to that shown by FIG. 7.

FIG. 9 is a view of the FIG. 8 substrate fragment at a processing stepsubsequent to that shown by FIG. 8.

FIG. 10 is a view of the FIG. 9 substrate fragment at a processing stepsubsequent to that shown by FIG. 9.

FIG. 11 is a view of the FIG. 10 substrate fragment at a processing stepsubsequent to that shown by FIG. 10.

FIG. 12 is a view of the FIG. 11 substrate fragment at a processing stepsubsequent to that shown by FIG. 11.

FIG. 13 is a view of the FIG. 12 substrate fragment at a processing stepsubsequent to that shown by FIG. 12.

FIG. 14 is a view of the FIG. 13 substrate fragment at a processing stepsubsequent to that shown by FIG. 13.

FIG. 15 is a diagrammatic sectional view of an alternate embodimentsemiconductor substrate fragment in process in accordance with an aspectof the invention.

FIG. 16 is a view of the FIG. 15 substrate fragment at a processing stepsubsequent to that shown by FIG. 15.

FIG. 17 is a view of the FIG. 16 substrate fragment at a processing stepsubsequent to that shown by FIG. 16.

FIG. 18 is a diagrammatic sectional view of another alternate embodimentsemiconductor substrate fragment in process in accordance with an aspectof the invention.

FIG. 19 is a view of the FIG. 18 substrate fragment at a processing stepsubsequent to that shown by FIG. 18.

FIG. 20 is a diagrammatic sectional view of still another alternateembodiment semiconductor substrate fragment in process in accordancewith an aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

The invention includes methods of forming field effect transistor gates,methods of forming field effect transistors, and methods of formingintegrated circuitry comprising a transistor gate array and circuitryperipheral to the gate array. The discussion proceeds primarily withreference to forming integrated circuitry comprising a transistor gatearray and circuitry peripheral to the gate array, while the artisan willappreciate aspects of the invention apply to forming a single fieldeffect transistor as well as to multiple field effect transistors, andone or more field effect transistor gates thereof.

Referring initially to FIG. 1, a semiconductor substrate in process isindicated generally with reference 10. In the context of this document,the term “semiconductor substrate” or “semiconductive substrate” isdefined to mean any construction comprising semiconductive material,including, but not limited to, bulk semiconductive materials such as asemiconductive wafer (either alone or in assemblies comprising othermaterials thereon), and semiconductive material layers (either alone orin assemblies comprising other materials). The term “substrate” refersto any supporting structure, including, but not limited to, thesemiconductive substrates described above. Substrate 10 is depicted ascomprising an array area or region 12 within which a field effecttransistor gate array will be fabricated and a peripheral circuitry area14 peripheral to gate array area 12. By way of example only, array area12 might be utilized for fabrication of memory circuitry, for exampleDRAM circuitry, while peripheral circuitry area 14 might include controlcircuitry for operating/controlling memory circuitry within array area12. Alternate configurations are of course contemplated, for exampleutilizing gate arrays and field effect transistors within logic, controlor other circuitries.

Substrate 10 is depicted as comprising semiconductive material 11, forexample bulk monocrystalline silicon. Other semiconductive materialsubstrates are also of course contemplated, for examplesemiconductor-on-insulator substrates, and whether existing or yet-to-bedeveloped. Semiconductive material 11 is ideally suitably backgrounddoped, or doped to form a doped well, to be of a suitable conductivitytype(s) and concentration(s). Exemplary preferred trench isolationregions 13, 15, 16, 17 and 18 have been fabricated relative tosemiconductive substrate material 11.

Referring to FIG. 2, masking material 20 has been formed oversemiconductive material 11 of substrate 10. Such is depicted ascomprising an innermost pad oxide layer 22 (exemplary preferredthickness range of from 30 Angstroms to 100 Angstroms), a masking layer24 of different composition to that of material 22 received overmaterial 22 (a preferred exemplary thickness range being from 50Angstroms to 300 Angstroms), and a masking layer 26 formed over and ofdifferent material to that of masking layer 24 (an exemplary preferredthickness range being from 1,000 Angstroms to 3,000 Angstroms). Some orall of masking material 20 might be sacrificial, thereby beingultimately removed from the substrate. Accordingly, some portions or allof masking material 20 might be any of electrically insulative,semiconductive, or conductive. An exemplary preferred material for layer24 is silicon nitride, while an exemplary preferred material for layer26 is undoped silicon dioxide. A further exemplary alternate embodiment,and by way of example, forms layer 24 to comprise silicon dioxide andlayer 26 to comprise silicon nitride. Regardless and accordingly in butonly one preferred implementation, masking material 20 comprises silicondioxide and silicon nitride, and in a more preferred embodimentcomprises silicon dioxide received over silicon nitride.

In one preferred implementation, layer 26 can be considered ascomprising an outer insulative material layer and layer 24 can beconsidered as comprising an inner insulative material layer, wherein theouter insulative material layer is selectively etchable relative to theinner insulative material layer, and independent of whether anotherinsulative material layer (such as layer 22) is received inwardly ofinner insulative material layer 24. In one preferred implementation,outer insulative material layer 26 is thicker than inner insulativematerial layer 24, and in one preferred implementation as shown,contacts inner insulative material layer 24. Further in the depictedexemplary embodiment, outer insulative material layer 26 is theoutermost material of masking material 20 at least at the conclusion ofits patterning. Further, layer 24 is preferably thicker than layer 22 inbut one exemplary implementation.

Referring to FIG. 3, array circuitry trenches 28 have been formedthrough masking material 20. An exemplary preferred technique includesphotolithographic patterning and etch using one or more photoresist orother layers (not shown). FIG. 3 depicts such photoresist or otherlayers as having been removed over masking material 20, although some orall of such might remain at the conclusion of the FIG. 3 processingwhere photolithography is utilized.

Referring to FIG. 4, masking material 20 has been utilized as a mask toform array circuitry trenches 30 into semiconductive material 11.Accordingly in one preferred embodiment, depicted trenches 28 and 30 areformed using a single masking step, for example utilizingphotolithography. An exemplary preferred depth range for trenches 30within semiconductive material 11 from an outer surface thereof is from300 Angstroms to 2,500 Angstroms.

Referring to FIG. 5, gate dielectric material 32 has been formed withintrenches 30 in semiconductive material 11. In one preferredimplementation, at least a majority of gate dielectric material 32 isformed by thermal oxidation of semiconductive material 11 withintrenches 30. The depicted exemplary embodiment depicts essentially allof such gate dielectric material having been formed by thermaloxidation, although deposition of gate dielectric material with orwithout thermal oxidation of material 11 within array trenches 30 isalso of course contemplated.

Referring to FIG. 6, array gate material 34 has been deposited withinarray circuitry trenches 28 within masking material 20 and within arraycircuitry trenches 30 within semiconductive material 11, and over gatedielectric material 32. Preferably, array gate material 34 is depositedto at least fill trenches 28 and 30, and most preferably to overfillsuch trenches and also depositing gate material 34 to cover maskingmaterial 20. Exemplary preferred materials 34 include conductively dopedsemiconductive materials, such as conductively doped polysilicon eitherin situ doped during deposition or subsequently. Other conductivematerials might also be utilized, such as conductive metal or metalcompounds but are not preferred at this point in the process.

Referring to FIG. 7, after depositing array gate material 34, peripheralcircuitry trenches 36 have been formed through masking material 20 and,in the depicted embodiment where material 34 is received thereover, alsothrough array gate material 34. FIG. 7 also depicts in oneimplementation fabrication of a grounded gate trench 37 through maskingmaterial 20 within array region 12, for example over one or more of thetrench isolation regions. In the context of this document, a groundedgate is an isolation gate which is fabricated to be received over atleast some field isolation and held at ground or other suitablepotential for providing an isolation function towards precluding orreducing formation of parasitic field effect transistor current flowbeneath or around field isolation regions. If desired, some or all oftrenches 36, 37 might be fabricated to etch/extend into material ofsemiconductive material 11 and/or field/trench isolation material.

Referring to FIGS. 7 and 8, preferred embodiment trenches 36, 37preferably expose semiconductive material 11 of substrate 10. FIG. 8depicts one preferred implementation wherein a gate dielectric layer 38is formed over exposed semiconductive material 11 within peripheralcircuitry trenches 36. Such might be formed, by way of example only, bya thermal oxidation wherein at least a majority of the gate dielectriclayer is comprised of oxidized semiconductive material (as shown). Suchmight also of course be combined with or substituted by deposition of agate dielectric layer with or without thermal oxidation of substratematerial 11. Further in the depicted exemplary embodiment, gatedielectric layer 38 also essentially forms over (and “on” as shown)array gate material 34, and will typically be subsequently removed fromthereover as described below. Regardless, the gate dielectric material38 might be the same or different as gate dielectric material 32 of thearray circuitry trenches 30, thereby enabling optimization of gatedielectric for different areas of circuitry. A preferred manner offorming trenches 36 and 37 is in a single masking step common to theformation of both types of trenches, for example utilizingphotolithography. In certain implementations, one or both of trenches 36and 37 might not be formed at all, or at other times if formed, andwhich is described below by way of example only in possible likelyalternative embodiments.

Regardless, FIG. 7 depicts one exemplary preferred embodiment whereingrounded gate trenches in the array and peripheral circuitry trenchesare formed in the same masking step. Further, of course, grounded gatetrenches might also be fabricated within peripheral circuitry area 14.

Referring to FIG. 9, peripheral circuitry gate material 40 has beendeposited within peripheral circuitry trenches 36 within maskingmaterial 20, and in the depicted exemplary embodiment within thecorresponding peripheral circuitry trenches also formed within arraygate material 34. Gate material 40 might be the same as or differentfrom material 34, thereby enabling optimization of conductivity typeand/or work function of the conductive gate material being formed fordifferent gates. Further in the depicted exemplary embodiment,peripheral circuitry gate material 40 is also utilized in thefabrication of grounded gates, depositing also within grounded gatetrenches 37. In the depicted exemplary preferred embodiment, peripheralcircuitry gate material 40 is deposited to a thickness to at least fill,and preferably overfill, peripheral circuitry trenches 36 withperipheral circuitry gate material 40, and to at least fill, andpreferably overfill, grounded gate trenches 37.

Referring to FIG. 10, array gate material 34, peripheral circuitry gatematerial 40, and dielectric layer 38 therebetween have been removedselectively relative to and outwardly exposes masking material 20effective to isolate the respective gate materials within the respectivetrenches in masking material 20 and in semiconductive material 11 wheresuch are so formed. In the context of this document, a selective removalrequires removal (for example by etching or other means) at a rate whichremoves one material relative to another at 2:1 or greater. In thedepicted exemplary embodiment, such removing has been effective torecess gate materials 34 and 40 within the depicted trenches 28, 36 and37 formed within masking material 20. Exemplary preferred techniquesinclude any one or combination of chemical mechanical polishing, resistetch back or timed chemical etching. Where, for example, materials 34and 40 comprise polysilicon and outer layer 26 of masking material 20comprises silicon nitride, an exemplary etching chemistry capable ofproducing the FIG. 10 construction in a timed etch includes tetramethylammonium hydroxide followed by exposure to a hydrofluoric acid solution.

Referring to FIG. 11, an exemplary higher conductive layer 42 has beendeposited (i.e., a refractory metal, other metal, or metal silicide) andpolished or etched back, followed by deposition of an insulativematerial layer 44 followed by polishing or other etch back of it. Suchthereby, in one exemplary preferred embodiment, caps recessed gatematerials 34 and 40 within masking material 20 with insulative material44. In one preferred embodiment, insulative material 44 is of commoncomposition to that of inner layer 24 of masking material 20 where suchis formed of insulative material. Accordingly by way of example only,materials 44 and 24 might comprise silicon nitride where material 26comprises silicon dioxide, or the reverse in but preferred embodiments.

Referring to FIG. 12 and in but one preferred embodiment, outer layer 26of masking material 20 has been etched selectively relative to innerlayer 24 and to capping insulative material 44 received over recessedgate materials 34 and 40. In one preferred implementation, an aspect ofthe invention includes forming gate dielectric material within thetrenches, for example material 32, prior to removing silicon nitride ofthe masking material when such is utilized.

Referring to FIG. 13 and in but one preferred embodiment, insulativematerial 50 preferably of common composition to that of inner insulativematerial layer 24 of masking material 20 has been deposited oversubstrate 10 as shown.

Referring to FIG. 14, material 50 and material 24 have beenanisotropically etched effective to form insulative sidewall spacers 52about gate materials 34, 40 and 42. Some or all of pad oxide layer 22(when such is utilized) might be removed earlier or at this point in theprocess, or some might remain as part of the finished circuitryconstruction. Regardless in one preferred embodiment, aspects of theinvention include removing at least a majority of the masking materialat some point after at least gate material 34 has been deposited. Inmost preferred embodiments, such methods of forming field effecttransistor gates, field effect transistors, and transistor gate arraysand circuitry peripheral to the gate array are preferably void ofphotolithographic patterning of any one or combination of gate materials34, 38 and 42 after such has/have been deposited.

FIG. 14 depicts fabrication of source/drain regions 56, with such mostpreferably being formed within semiconductive material 11 of substrate10. Such might be formed by one or a combination of ion implants ofsuitable conductivity enhancing dopant(s) during any of the aboveprocessing steps. Further of course, other channel, channel stopping, orother implants, whether existing or yet-to-be developed, could beconducted during any of the above processing.

Alternate embodiments are of course contemplated with the invention onlybeing limited by the claims as literally worded without readinglimitations from other claims, the drawings, or specifications into theclaims. By way of example only, a few exemplary alternate embodimentswill now be described. Referring to FIG. 15, such depicts asemiconductor substrate 10 a corresponding to or a substitute for theFIG. 4 depicted processing with respect to the first describedembodiments. Like numerals from the first described embodiments havebeen utilized where appropriate, with differences being indicated withthe suffix “a” or with different numerals. FIG. 15 depicts substratefragment 10 a which includes the forming of grounded gate trenches 37 athrough masking material 20 in the array in the same masking step inwhich array circuitry trenches 28 and 30 are formed. Further by way ofexample only in the depicted embodiment, grounded gate trenches 37 ahave been formed to extend into the trench isolation regions, such astrench isolation region 15.

Referring to FIG. 16, gate dielectric material 32 has been formed, andgate material 34 a has been deposited to within grounded gate trench 37a.

Referring to FIG. 17, subsequent processing has occurred to a point offabrication of anisotropically etched insulative sidewall spacers 52 andsource/drain regions 56. Processing, materials, etc. are otherwisepreferably as provided above in the first described embodiments of FIGS.1-14.

Further by way of example only, another exemplary embodiment processingwith respect to a substrate fragment 10 b is described with reference toFIGS. 18 and 19. Like numerals from the first and second describedembodiments have been utilized where appropriate, with differences beingindicated with the suffix “b” or with different numerals. FIG. 18corresponds in processing sequence to that of FIG. 4, and wherein one ormore peripheral circuitry trenches 36 b have been formed commensuratewith formation of array circuitry trenches 28, 30. Such might beadvantageously utilized wherein certain transistors of the peripheralcircuitry and the array circuitry are desired to be of the sameconductivity type and/or work function, and/or other desired property.

FIG. 19 depicts subsequent gate dielectric 32 fabrication, gate material34 b deposition, and then subsequent patterning of masking material 20 band gate material 34 b to form, by way of example only, grounded gatetrenches 37 b and another peripheral circuitry trench 36 b. Accordingly,some of the peripheral circuitry trenches might be formed commensuratewith formation of the array circuitry trenches. Subsequent processingcould occur, for example, analogously or otherwise to that depicted anddescribed relative to FIGS. 8-14.

FIG. 20, by way of example only, depicts alternate exemplary processingwith respect to a substrate fragment 10 c. Like numerals from theabove-described embodiments have been utilized where appropriate, withdifferences being indicated with the suffix “c” or with differentnumerals. FIG. 20 depicts processing whereby array trenches 28, 30 havebeen fabricated using a masking step separate from fabrication of anyother line trenches in the depicted cross section. Subsequent thereto,grounded gate isolation trenches 37 and one peripheral circuitry gatetrench 70 have been fabricated in a common masking step, and gatematerial 40 c deposited thereover. Thereafter, another masking has beenconducted through masking material 20 and the previously deposited gatematerials to form another peripheral circuitry trench 74. Gatedielectric 71 has been formed (for example by any of the above describedprocesses relative to gate dielectric material fabrication).Subsequently, gate material 76 has been deposited which may be the sameor different from any of the above exemplary gate materials. Processingcould otherwise ideally proceed subsequently commensurate with ordifferent from the above-described embodiments as depicted and describedrelative to FIGS. 8-14 for example.

Aspects of the invention also encompass a method of forming field effecttransistor gates which include forming masking material oversemiconductive material of the substrate, and where the substratecomprises a trench isolation region. Exemplary embodiments, by way ofexample only, are those described above. In a common masking step, afirst trench is formed through the masking material and into thesemiconductive material and a second grounded isolation gate trench isformed through the masking material over the field isolation region.Such masking step in one preferred implementation comprisesphotolithography. Further in one implementation, the second groundedisolation gate trench might be fabricated to extend within the fieldisolation region during the stated common masking step.

Subsequently in a common deposition step, gate material is depositedwithin the first trench and the second trench. Such common depositionstep preferably at least fills, and more preferably overfills, the firstand second trenches with the gate material. In one preferredimplementation, at least a majority of the masking material is removedafter depositing the gate material. In one preferred implementation, theprocess is void of any photolithographic patterning of the gate materialafter its deposition. In one implementation, the gate material asdeposited covers the masking material with gate material, and theprocess further comprises removing the gate material selectivelyrelative to and exposing of the masking material effective to isolatethe gate material within the first and second trenches.

In one implementation, an aspect of the invention encompasses a methodof forming integrated circuitry comprising a transistor gate arrayincluding first gates and second grounded isolation gates. Maskingmaterial is formed over semiconductive material of a substrate, and thesubstrate comprises trench isolation regions. First trenches are formedthrough the masking material and into the semiconductive material forthe first gates. Second grounded isolation gate trenches are formedthrough the masking material over the field isolation regions for thesecond grounded isolation gates. Gate material is deposited within thefirst and second trenches.

The first and second trenches might be formed at the same time or atdifferent times, for example either before or after the other. Thesecond trenches might be formed within the field isolation regions orreceived only outwardly thereof.

Depositing of the gate material within the first and second trenchesmight occur in the same deposition step, or might occur in differentdeposition: steps. Further, some of the depositing of the gate materialwithin the first and second trenches might occur in the same depositionstep, and another of some of the depositing of gate material within thefirst and second trenches might occur in different deposition steps.Regardless and preferably, depositing of the gate material at leastfills, and even more preferably overfills, the first and second trencheswith the gate material. Processing is otherwise preferably as describedabove with respect to the other embodiments.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A method of forming a field effect transistor, comprising: formingmasking material over semiconductive material of a substrate; forming atrench through the masking material and into the semiconductivematerial; forming gate dielectric material within the trench in thesemiconductive material; depositing gate material within the trench inthe masking material and within the trench in the semiconductivematerial over the gate dielectric material; and forming source/drainregions.
 2. The method of claim 1 wherein the masking material comprisessilicon dioxide received over silicon nitride.
 3. The method of claim 1wherein forming at least a majority of the gate dielectric materialcomprises thermal oxidation of the semiconductive material within thetrench.
 4. The method of claim 1 wherein the depositing of the gatematerial at least fills the trench in the masking material and thetrench in the semiconductive material with the gate material.
 5. Themethod of claim 1 wherein the depositing of the gate material overfillsthe trench in the masking material and the trench in the semiconductivematerial with the gate material.
 6. The method of claim 1 wherein thesource/drain regions are formed within the semiconductive material ofthe substrate.
 7. The method of claim 1 comprising removing at least amajority of the masking material after depositing the gate material. 8.The method of claim 1 being void of photolithographic patterning of thegate material after its deposition.
 9. The method of claim 1 whereindepositing the gate material covers the masking material with the gatematerial, and comprising removing the gate material selectively relativeto and exposing the masking material effective to isolate the gatematerial within the trench in the masking material and the trench in thesemiconductive material.
 10. A method of forming a field effecttransistor, comprising: forming masking material over semiconductivematerial of a substrate, the masking material comprising an outerinsulative material layer and an inner insulative material layer, theouter insulative material layer being selectively etchable relative tothe inner insulative material layer; forming a trench through themasking material and into the semiconductive material; forming gatedielectric material within the trench in the semiconductive material;depositing gate material within the trench in the masking material andwithin the trench in the semiconductive material over the gatedielectric material; recessing the gate material within the trench inthe masking material; capping the recessed gate material within thetrench within the masking material with insulative material of commoncomposition to that of the inner insulative material layer; etching theouter insulative material layer selectively relative to the innerinsulative material layer and to the capping insulative materialreceived over the recessed gate material; after etching the outerinsulative material layer, depositing insulative material of commoncomposition to that of the inner insulative material layer;anisotropically etching the insulative material of common composition tothat of the inner insulative material layer effective to form insulativesidewall spacers about the gate material; and forming source/drainregions.
 11. The method of claim 10 wherein the outer insulativematerial layer is thicker than the inner insulative material layer. 12.The method of claim 10 wherein the outer insulative material layercontacts the inner insulative material layer.
 13. The method of claim 10wherein the outer insulative material layer is the outermost material ofthe masking material.
 14. The method of claim 10 further comprisinganother insulative material layer received inwardly of the innerinsulative material layer.
 15. The method of claim 10 wherein the outerinsulative material layer comprises silicon dioxide and the innerinsulative material layer comprises silicon nitride.
 16. The method ofclaim 10 wherein the outer insulative material layer comprises siliconnitride and the inner insulative material layer comprises silicondioxide.
 17. The method of claim 10 wherein the depositing of the gatematerial at least fills the trench in the masking material and thetrench in the semiconductive material with the gate material.
 18. Themethod of claim 10 wherein the source/drain regions are formed withinthe semiconductive material of the substrate.
 19. The method of claim 10being void of photolithographic patterning of the gate material afterits deposition.
 20. A method of forming a field effect transistor gate,comprising: forming a silicon nitride-comprising masking material oversemiconductive material of a substrate; forming a trench through thesilicon nitride-comprising masking material and into the semiconductivematerial; removing silicon nitride of the masking material after formingthe trench into the semiconductive material; prior to removing siliconnitride of the masking material, forming gate dielectric material withinthe trench in the semiconductive material; and depositing gate materialwithin the trench in the semiconductive material over the gatedielectric material. 21-29. (canceled)
 30. A method of formingintegrated circuitry comprising a transistor gate array and circuitryperipheral to the gate array, comprising: forming masking material oversemiconductive material of a substrate; forming array circuitry trenchesthrough the masking material and into the semiconductive material;depositing array gate material within the array circuitry trenches inthe masking material and within the array circuitry trenches in thesemiconductive material; after depositing the array gate material,forming peripheral circuitry trenches through the masking material; anddepositing peripheral circuitry gate material within the peripheralcircuitry trenches within the masking material. 31-45. (canceled)
 46. Amethod of forming integrated circuitry comprising a transistor gatearray and circuitry peripheral to the gate array, comprising: formingmasking material over semiconductive material of a substrate; formingarray circuitry trenches through the masking material and into thesemiconductive material; depositing array gate material within the arraycircuitry trenches in the masking material and within the arraycircuitry trenches in the semiconductive material; forming peripheralcircuitry trenches through the array gate material and through themasking material; and depositing peripheral circuitry gate materialwithin the peripheral circuitry trenches within the array gate materialand within the masking material. 47-60. (canceled)
 61. A method offorming field effect transistor gates, comprising: forming maskingmaterial over semiconductive material of a substrate, the substratecomprising a trench isolation region; in a common masking step, forminga first trench through the masking material and into the semiconductivematerial and forming a second grounded isolation gate trench through themasking material over the trench isolation region; and in a commondeposition step, depositing gate material within the first trench andsecond trench. 62-69. (canceled)
 70. A method of forming integratedcircuitry comprising a transistor gate array including first gates andsecond grounded isolation gates, comprising: forming masking materialover semiconductive material of a substrate, the substrate comprisingtrench isolation regions; forming first trenches through the maskingmaterial and into the semiconductive material for the first gates;forming second grounded isolation gate trenches through the maskingmaterial over the trench isolation regions for the second groundedisolation gates; and depositing gate material within the first andsecond trenches. 71-84. (canceled)